This invention relates to a plasmid naturally present in Nocardia orientalis and use thereof as a vector and to derive other vectors.
A vector used in expression or cloning as an autonomous unit contains a functional region which allows the vector to replicate autonomously in host cells. Such regions are referred to as replicons or autonomously replicating segments. Known vectors are derived from naturally occurring molecules, often double stranded DNA plasmids. Such molecules can be used as a source of functional regions, including replicons, genes expressing desired products including products which confer phenotypically selectable traits, and transcription and translation regulatory regions.
Plasmids carrying regions which function in members of the Order Actinomycetales, and especially of the Family Streptomycetaceae, are of interest because of the large number of products, particularly secondary metabolites such as antibiotics, which are produced by the Actinomycetales. Such plasmids can serve as sources of functional regions for use in genetic engineering of Actinomycetales.
Techniques useful in genetic engineering of Streptomycetacease are reviewed by Chater et al. in Current Topics in Microbiology and Immunology 96: 69-95 (1982), whichis incorporated by reference herein as though fully set forth. Such techniques are now generally well known and have resulted in the finding of several plasmids and other vectors useful in genetic engineering of Actinomycetales.
For example, Chater et al., cited above, report three families of Streptomyces plasmids. These are represented by SCP2, SLP1 and pIJ101. Bibb et al., Mol. Gen. Genet. 184: 230-240 (1981) and U.S. Pat. No. 4,360,597, report that SLP1 resulted from excision of a fragment of S. coelicolor A3(2) chromosomal DNA upon crossing with S. lividans 66.
Other families of Streptomyces vectors derived from naturally-occurring plasmids or from excision of chromosomal DNA have been reported. Additionally, various derivatives of Streptomyces vectors are known, including hybrid vectors. For example, Schottel et al., J. Bacteriol. 146: 360-368 (1981), describe construction of hybrid plasmids carrying E. coli and streptomyces replicons.
Many conjugative Streptomyces plasmids, including the SCP2, SLP1 and PIJ101 plasmids, cause a lethal zygosis-like phenomenon when a plasmid-bearing strain is crossed with a non-plasmid-bearing strain such as S. lividans 1326. This property can be useful as a test for presence of plasmids in Streptomyces. See, Hopwood et al., "Microbiology 1981", edit. by Schlessinger, Am. Soc. Microbiol., Washington, D.C. 1981, pp. 367-370.
Hopwood et al., Bacteriol. Rev. 41(3): 595-635 (1979); Akagawa et al., J. Antibiot. 32(6): 610-620 (1979); Hayakawa et al., J. Antibiot. 32(12): 1348-1350 (1979); and Toyama et al., J. Antibiot. 35(3): 369-373 (1982) report plasmid involvement in antibiotic synthesis in a variety of Streptomyces sp.
Vancomycin production by strains of N. orientalis has been reported, for example, by McCormick et al., Antibiotics Annual 1955/56, pp. 606-611, Pittenger et al., Antibiot. Chemother. 6 (11): 642-647 (1956), U. K. Specification No. 795,289 and McCormick et al., U.S. Pat. No. 3,067,099.
Reh et al., J. Gen. Micro., 126, 327-336 (1981) disclose genetic evidence that suggests the presence of a conjugative plasmid in Nocardia opaca strain lb. Reh et al. do not disclose the physical isolation or characterization of such a plasmid.